Intensity of the Earth's magnetic field: Evidence for a Mesozoic dipole low

Prévot, Michel; Derder, M. E. M.; McWilliams, Michael; Thompson, John

doi:10.1016/0012-821x(90)90104-6

Cited by 173 publications

(91 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Additional supporting evidence for our model comes from paleomagnetic intensity trends before and during the CNS, and in particular, the evidence for a Mesozoic Dipole Low (or MDL; Prevot et al, 1990), roughly contemporaneous with the hyperreversing period in the Jurassic during 160-180 Ma. Controversy surrounds the overall significance of the MDL, with some studies finding a general inverse correlation between paleointensity and reversal frequency (Channell et al, 1982;Tarduno and Cottrell, 2005), while other studies questioning whether such a correlation exists (Ingham et al, 2014).…”

Section: Supporting Evidencesupporting

confidence: 57%

Mantle superplumes induce geomagnetic superchrons

Olson

Amit

2015

Front. Earth Sci.

View full text Add to dashboard Cite

We use polarity reversal systematics from numerical dynamos to quantify the hypothesis that the modulation of geomagnetic reversal frequency, including geomagnetic superchrons, results from changes in core heat flux related to growth and partial collapse of the two seismically-imaged lower mantle superplumes. We parameterize the reversal frequency sensitivity from numerical dynamos in terms of average core heat flux normalized by the difference between the present-day core heat flux and the core heat flux at geomagnetic superchron onset. A low-order polynomial fit to the 0-300 Ma Geomagnetic Polarity Time Scale (GPTS) reveals that a decrease in core heat flux relative to present-day of ∼30% can account for the Cretaceous Normal Polarity and Kiaman Reverse Polarity Superchrons, whereas the hyper-reversing periods in the Jurassic require a core heat flux equal to or higher than present-day. Possible links between GPTS transitions, large igneous provinces (LIPs), and the two lower mantle superplumes are explored. Lower mantle superplume growth and collapse induce GPTS transitions by increasing and decreasing core heat flux, respectively. Age clusters of major LIPs postdate transitions from hyper-reversing to superchron geodynamo states by 30-60 Myr, suggesting that superchron onset may be contemporaneous with LIP-forming instabilities produced during collapses of lower mantle superplumes.

show abstract

Section: Supporting Evidencesupporting

confidence: 57%

Mantle superplumes induce geomagnetic superchrons

Olson

Amit

2015

Front. Earth Sci.

View full text Add to dashboard Cite

show abstract

“…Summary Prevot et al [1990] suggested the existence of a 'Mesozoic Dipole Low,' although their analysis was unable to identify the precise age of the MDL extremities.They suggested that its onset may have followed a high field period during the Early Jurassic, and its termi nation may have been linked to a major dis sociation of D"at around 100 Ma. Perrin and Shcherbakov [1997] were unable to distinguish, statistically between two lows (separated by a brief return to high values) or a single low in 260-120 Ma period.They also addressed the issue of MDL reliability, recognizing that many authors were skeptical of its existence.…”

Section: The MDL Debate: a Briefmentioning

confidence: 99%

“…One proposed major feature in the VDM record is the so-called Mesozoic Dipole Low (MDL), during which the VDM appeared to be about one-third of its present value for a period of at least 50 m.y [Prevot et al, 1990] .The validity of this feature has recently been questioned by Goguitchaichvili et al [2002a,b], who con cluded that the MDL hypothesis is probably untenable.This conclusion was reached fol lowing an analysis of the 160-5 Ma part of the VDM record and the recognition that the Early Cretaceous VDM may have been similar to, or possibly much higher than, the current value ( Figure 1). Goguitchaichvili et al [2002a,b] present valuable new data and an addition to the general debate, but unfortunately, they reach their conclusion by using potentially flawed reasoning.…”

Section: Pages 97103-104mentioning

confidence: 99%

Does the Mesozoic dipole low really exist?

Thomas¹,

Biggin²

2003

EoS Transactions

View full text Add to dashboard Cite

Documenting variations in the virtual dipole moment (VDM) of the geomagnetic field through geologic time has recently been the subject of considerable interest, not the least because a detailed and reliable VDM record would provide a key constraint for geodynamo modeling. Such a record would also inform the debate concerning issues related to Earth's geodynamic evolution, such as how the geomagnetic field responds to stages in supercontinent cycling. The relationship between variations in geomagnetic polarity and field intensity with lowermost mantle (LMM) processes is fundamental, but the paucity of the VDM record has focused research on the links between polarity and LMM processes. Nonetheless, authors agree on the crucial need to produce a detailed VDM record in which we can place sufficient confidence to allow these major issues to be addressed [e.g., Biggin and Thomas, 2003; Heller et al., 2002; Riisager et al., 2002; Tarduno et al., 2001; Selkin and Tauxe, 2000].

show abstract

“…Certain properties of the geomagnetic field, such as the frequency of reversals and perhaps also the average dipole strength, vary on a time scale of 108 years (COURTILLOT and BESSE, 1987;PREVOT et al, 1990). Since this time scale does not arise naturally from core properties, but is characteristic of mantle convection we may seek an explanation in terms of mantle control of core processes.…”

Section: Introductionmentioning

confidence: 99%

Does Lower Mantle Tomography Indicate Temperature Variations That Affect the Core?

Stacey

1993

J. geomagn. geoelec

View full text Add to dashboard Cite

Intensity of the Earth's magnetic field: Evidence for a Mesozoic dipole low

Cited by 173 publications

References 56 publications

Mantle superplumes induce geomagnetic superchrons

Mantle superplumes induce geomagnetic superchrons

Does the Mesozoic dipole low really exist?

Does Lower Mantle Tomography Indicate Temperature Variations That Affect the Core?

Contact Info

Product

Resources

About